Inner surface modification of polyurethane ureteral stents using plasma-enhanced chemical vapor deposition to improve the resistance to encrustation in a pig model.

PURPOSE: We developed a ureteral stent with a non-fouling inner surface using plasma micro-surface modification technology. This study aimed to evaluate the safety and efficacy of this stent in animal model. MATERIALS AND METHODS: Ureteral stents were placed in five Yorkshire pigs. A bare stent was inserted on one side and an inner surface-modified stent was inserted on the other side. Two weeks after stenting, laparotomy was performed to harvest the ureteral stents. The changes in the inner surface were grossly evaluated using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). In addition, if encrustation was observed, the components were analyzed using Fourier transform infrared spectroscopy. Urine cultures were used for safety assessment. RESULTS: In all models, urine cultures did not show any bacterial growth before and after stenting, and stent-related complications were not identified. Hard materials were palpable in four bare models. Palpable material was not identified in the modified stent. Calcium oxalate dihydrate/uric acid stones were identified in two bare stents. In the SEM images with EDS, biofilm formation was confirmed in the bare stents. Biofilm formation was significantly less on the inner surface of the modified stent, and the intact surface of the modified stent was larger than that of the bare stent. CONCLUSIONS: The application of a specialized, plasma-enhanced, chemical vapor deposition technology to the inner surface of ureteral stents was safe and showed resistance to biofilm formation and encrustation.

Inner surface modification of ureteral stent polyurethane tubes based by plasma-enhanced chemical vapor deposition to reduce encrustation and biofilm formation.

Encrustation and/or biofilm formation in ureteral stents are major causes of obstruction and reduce the lifetime of a ureteral stent. In this study, the inner surfaces of polyurethane (PU) tubes (inner and outer diameters of 1.2 and 2.0 mm, respectively) were reformed with Ar, O2, and C2H2 gases using specialized plasma-enhanced chemical vapor deposition techniques for the first time. Then, the modified PU tubes were immersed in urine for 15 days, and the characteristics of the inner surfaces were analyzed. Depending on the modification procedure, the corresponding inner surface exhibited different chemical properties and different rates of encrustation and biofilm formation. For a hydrophilic surface treated with Ar and O2, encrustation and biofilm formation increased, while for the C2H2 coating, the development of encrustation and biofilm reduced by more than five times compared with the untreated bare PU tube. This study demonstrated that inner plasma surface modification of ureteral stents greatly enhances resistance to encrustation and biofilm formation.

Enhanced culturing of adipose derived mesenchymal stem cells on surface modified polystyrene Petri dishes fabricated by plasma enhanced chemical vapor deposition system.

Mesenchymal stem cells (MSCs) have received considerable attention as therapeutic cells for regenerative medicine and tissue engineering, because of their ability to replace damaged cells or regenerate surrounding cells. There are many technical difficulties in the mass production of high-quality stem cells because the stem cells must maintain an efficient proliferative cell state during in vitro culture. The results of this study show that plasma surface-modification enhanced significantly the culture of adipose-derived mesenchymal stem cells (ASCs) on the polystyrene (PS) Petri dishes. Ar, O2 , pyrrole, and 4,7,10-trioxa-1,13-tridecanediamine (TTDDA) were used as the gas and/or precursors for plasma modification. Specifically, surfaces of PS Petri dishes, coated with plasma polymerized pyrrole (ppPy) and plasma polymerized TTDDA (ppTTDDA) were found to contain amine and carboxyl functional groups, respectively. Ar and O2 plasma-treated PS Petri dishes have similar culture abilities (±1.2 times) to commercially available tissue culture polystyrene (TCPS) dishes, and PS Petri dishes coated with ppPy and ppTTDDA have significantly enhanced culture abilities (2.4 times) at 96 hr compared with TCPS dishes. Western blotting was performed using antibodies against stem cell marker proteins to confirm the stemness properties of stem cells, in the sense that the expressions of the antibody proteins such as CD44, CD73, and CD105 in plasma modified samples were similar to or higher than those in TCPS dishes.

Surface modification of polystyrene Petri dishes by plasma polymerized 4,7,10-trioxa-1,13-tridecanediamine for enhanced culturing and migration of bovine aortic endothelial cells.

Plasma surface modification is an effective method for changing material properties to control cell behavior on a surface. This study investigates the efficiency of a plasma polymerized 4,7,10-trioxa-1,13-tridecanediamine (ppTTDDA) film coated on a polystyrene (PS) Petri dish, which is a biocompatible surface with carbon- and oxygen-based chemical species. The adhesion, proliferation, and migration properties of bovine aortic endothelial cells (BAECs) were profoundly enhanced in the ppTTDDA-coated PS Petri dishes without extracellular matrix (ECM) proteins, when compared with the uncoated PS Petri dishes. These observations indicate that ppTTDDA-coated PS Petri dishes can directly interact with cells, regardless of cell adhesion molecules. The increased cell affinity was attributed to the high concentration of carboxyl group on the surface of the ppTTDDA film. Such a carboxyl surface showed an excellent ability to promote culturing of BAECs. Plasma surface modification techniques are effective in improving biocompatibility and provide a surface environment for cell culture.

[Serum ALT and HBV DNA levels in patients with HBeAg-negative chronic hepatitis B].

BACKGROUND/AIMS: HBeAg-negative chronic hepatitis B (CHB) has a poor long-term prognosis. Since no precise clinically relevant HBV thresholds are known in HBeAg-negative CHB, the decision to treat is difficult. The aim of this study was to evaluate the levels of serum HBV DNA and transaminase and to investigate the correlation of these values in patients with HBeAg-negative CHB. METHODS: The study analyzed the sera from 82 patients with HBeAg-negative CHB, 61 men and 21 women. The mean age was 45 years. The patients were divided into two groups according to serum ALT levels: the patients with lower ALT level (n=52, UNL < ALT < 2 X UNL) and higher level (n=30, ALT >/= 2 X UNL). The level of serum HBV DNA was determined by the Cobas Amplicor HBV Monitor(TM) (Roche). RESULTS: The median serum HBV DNA level was 2.7 X 10(5) copies/mL in patients with HBeAg-negative CHB. The median serum HBV DNA level of patients with a higher ALT level (1.0 X 10(6) copies/mL) was significantly higher than that of patients with a lower ALT level (5.6 X 10(4) copies/mL)(p<0.001). The serum ALT level was correlated with serum HBV DNA levels in patients with HBeAg-negative CHB (r=0.416, p<0.001). The serum level of HBV DNA in patients with cirrhosis (median 2.0 X 10(5) copies/mL) did not differ from patients without cirrhosis (median 4.7 X 10(5) copies/mL). CONCLUSIONS: The level of serum HBV DNA was higher in patients with higher serum ALT level than it was in patients with lower serum ALT, and it was closely correlated with serum ALT levels in HBeAg-negative CHB.